<h2>Problem 291</h2>
<div style="color:#666;font-size:80%;">07 May 2010</div><br />
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<p>
A prime number <var>p</var> is called a Panaitopol prime if <img src="project/images/p_291_formula.gif" style="vertical-align:middle"/> for some positive integers<br /> <var>x</var> and <var>y</var>.
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<p>
Find how many Panaitopol primes are less than 5<img src='images/symbol_times.gif' width='9' height='9' alt='&times;' border='0' style='vertical-align:middle;' />10<img src="" style="display:none;" alt="^(" /><sup>15</sup><img src="" style="display:none;" alt=")" />.
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